The lead author and a PhD candidate at UQ’s School of Biomedical Sciences, Lachlan Harris, said the research was a significant contribution to understanding how the brain develops, and could help patients better understand their condition.

“Each unborn child has a certain number of stem cells in their developing brain,” Mr Harris said.

“These stem cells need to differentiate, at the right time during brain development, to make the right number of neurons.

“If these cells differentiate too early you get a smaller brain; if they take too long you get a larger brain, and both cases can lead to impaired brain function.

“We found that deficiency in a gene called Nuclear factor one (Nfix) leads to the development of larger brains – an attribute common in Sotos and Marshall Smith patients.”